1. Field of the Invention
This invention relates to mineral oil infusion of polypropylene to produce biodegradable plastic.
2. Description of the Related Art
It has been known that mineral oil mixed with polypropylene will produce a biodegradable plastic, however too much mineral oil mixed with the polypropylene will result in premature degradation of the plastic and too little mineral oil mixed with the polypropylene will result in the plastic not degrading as desired.
In the medical industry mineral oil has been mixed with polypropylene resulting in a lower cost plastic which is then disposable by incineration after use. The amount of mineral oil mixed with the polypropylene was not carefully controlled as the product was to have a short shelf life and then be incinerated, therefore exact mixtures for long shelf life and biodegradability in land fills was not a problem that was addressed.
In some prior art mineral oil and polypropylene mixing devices the mineral oil was mixed with the polypropylene in a hopper above a feed throat to a barrel with a screw for infusing the mineral oil into the polypropylene. The resulting mixture was not controlled for exact percentages in the mixture and mineral oil would escape the hopper-feed throat interface creating a potential fire hazard.
It is desired to have a plastic polypropylene product with a long shelf life for use in a disposable product which will biodegradably decay in a land fill in a reasonable amount of time. In order to obtain such a plastic the mixture of mineral oil to polypropylene should accurately controller to be about 11.5% mineral oil by weight.